1. Field of the Invention
The present invention relates to a viscosity-stable solution of polyurethaneureas and, more specifically, to such solutions without viscosity stabilizer additives.
2. Discussion of Background Art
Polyurethane solutions, generally dry-spun or wet-spun to make spandex, face a common problem of viscosity instability and gelation during storage prior to spinning. Such increases in viscosity can make the solution unusable for spinning into spandex and are, therefore, highly undesirable. U.S. Pat. No. 5,288,779 discloses the need for special additives to stabilize the solutions of polyurethaneureas, including those made from polyethers derived from tetrahydrofuran and 3-methyltetrahydro-furan, bis(4-isocyanatcocyclohexyl)methane, and ethylene diamine.